/[gxemul]/trunk/TODO
This is repository of my old source code which isn't updated any more. Go to git.rot13.org for current projects!
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revision 18 by dpavlin, Mon Oct 8 16:19:11 2007 UTC revision 44 by dpavlin, Mon Oct 8 16:22:56 2007 UTC
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1  $Id: TODO,v 1.175 2005/10/23 14:24:09 debug Exp $  $Id: TODO,v 1.556 2007/09/11 21:46:35 debug Exp $
2    
3  ===============================================================================  Some things, in no specific order, that I'd like to fix:
4    (Some items in this list are perhaps already fixed.)
5    
6  High priority stuff:  -------------------------------------------------------------------------------
7    
8    A first pass of installation regression testing of NetBSD 4.0 RC1 in GXemul:
9    
10  Old MIPS bintrans:          X  pmax (including X Windows out-of-the-box)
11            X  arc  (1.6.2 -> 4.0! Yay!)
12          x)  call/return address cache?             hpcmips
13               cobalt
14          x)  Turn the MIPS cpu family stuff into dyntrans.             evbmips
15               algor
16               sgimips
17               cats
18               evbarm
19               netwinder
20               prep         nej, 2.0 är senaste som funkar :(
21            X  macppc
22               pmppc
23            X  dreamcast
24            X  landisk
25    
26    X = done and worked fine
27    
28    -------------------------------------------------------------------------------
29    
30    Perform a second regression test pass, when the actual NetBSD 4.0 release
31    has happened.
32    
33            o)  Test all guest OSes.
34            o)  Update:
35                    URLs
36                    Versions
37    
38            o)  Make a new GXemul release:  0.4.6.1
39    
40    -------------------------------------------------------------------------------
41    
42    M88K:
43            o)  FIP != NIP + 4, in rte! (Simulate delayed branch stuff.)
44            o)  cpu_dyntrans.c: MEMORY_USER_ACCESS implementation for M88K!
45            o)  xmem: Set transaction registers!
46            o)  CMMUs:
47                    o)  Translation invalidations, could be optimized.
48                    o)  Move initialization from dev_mvme187 to somewhere
49                        more reasonable?
50            o)  Instruction trace by using bits of ??IP control regs.
51            o)  Interrupts (these are machine dependent, though).
52            o)  Implement devices etc. for one or more machine modes,
53                to get some guest OS running. OpenBSD/mvme88k on MVME187
54                seems to be the smartest path to follow for now.
55                    o)  VME bus device
56                    o)  PCC2
57                    o)  Cirrus Logic serial port controller
58            o)  Instruction disassembly, and implementation:
59                    o)  See http://www.panggih.staff.ugm.ac.id/download/GCC/info/gcc.i5
60                        for some strange cases of when "div" can fail (?)
61                    o)  Floating point stuff
62                    o)  "Graphics" instructions (M88110-specific)
63    
64    MIPS:
65            o)  Nicer MIPS status bits in register dumps.
66            o)  Floating point exception correctness.
67            o)  Fix this? Triggered by NetBSD/sgimips? Hm:
68                    to_be_translated(): TODO: unimplemented instruction:
69                    000000000065102c: 00200800 (d)  rot_00  at,zr,0
70            o)  Some more work on opcodes.
71                    x) MIPS64 revision 2.
72                            o)  Find out which actual CPUs implement the rev2 ISA!
73                            o)  DINS, DINSM, DINSU etc
74                            o)  DROTR32 and similar MIPS64 rev 2 instructions,
75                                which have a rotation bit which differs from
76                                previous ISAs.
77                    x) _MAYBE_ TX79 and R5900 actually differ in their
78                       opcodes? Check this carefully!
79            o)  Dyntrans: Count register updates are probably not 100% correct yet.
80            o)  (Re)implement 128-bit loads/stores for R5900.
81            o)  Coprocessor 1x (i.e. 3) should cause cp1 exceptions, not 3?
82                    (See http://lists.gnu.org/archive/html/qemu-devel/2007-05/msg00005.html)
83            o)  R4000 and others:
84                    x)  watchhi/watchlo exceptions, and other exception
85                        handling details
86            o)  MIPS 5K* have 42 physical address bits, not 40/44?
87            o)  R10000 and others:  (R12000, R14000 ?)
88                    x)  The code before the line
89                            /*  reg[COP0_PAGEMASK] = cpu->cd.mips.coproc[0]->tlbs[0].mask & PAGEMASK_MASK;  */
90                        in cpu_mips.c is not correct for R10000 according to
91                        Lemote's Godson patches for GXemul. TODO: Go through all
92                        register definitions according to http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi/hdwr/bks/SGI_Developer/books/R10K_UM/sgi_html/t5.Ver.2.0.book_263.html#HEADING334
93                        and make sure everything works with R10000.
94                        Then test with OpenBSD/sgi?
95                    x)  Entry LO mask (as above).
96                    x)  memory space, exceptions, ...
97                    x)  use cop0 framemask for tlb lookups
98                        (http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi/hdwr/bks/SGI_Developer/books/R10K_UM/sgi_html/t5.Ver.2.0.book_284.html)
99    
100    SuperH:
101            x)  Auto-generation of loads/stores! This should get rid of at least
102                the endianness check in each load/store.
103            x)  Experiment with whether or not correct ITLB emulation is
104                actually needed. (20070522: I'm turning it off today.)
105            x)  SH4 interrupt controller:
106                    x)  MASKING should be possible!
107            x)  SH4 DMA (0xffa00000)
108            x)  SH4 UBC (0xff200000)
109            x)  Store queues can copy 32 bytes at a time, there's no need to
110                copy individual 32-bit words. (Performance improvement.)
111            x)  SH4 BSC (Bus State Controller)
112            x)  Instruction tracing should include symbols for branch targets,
113                and so on, to make the output more human readable.
114            x)  SH3-specific devices: Pretty much everything!
115            x)  NetBSD/evbsh3, hpcsh! Linux?
116            x)  Floating point speed!
117            x)  Floating point exception correctness.
118            x)  Exceptions for unaligned load/stores. OpenBSD/landisk uses
119                this mechanism for its reboot code (machine_reset).
120    
121    Landisk SH4:
122            x)  When NetBSD/landisk 4.0 has been released, make sure it works
123                in the emulator. (Update documentation, etc.)
124                NetBSD HEAD (as of April 2007) hangs during bootup, because it
125                turns on/off interrupts in an unfortunately synchronized way
126                with dyntrans. This needs to be fixed.
127    
128    Dreamcast:
129            x)  G2 DMA
130            x)  LAN adapter (dev_mb8696x.c).  NetBSD root-on-nfs.
131            x)  PVR:  Lots of stuff. See dev_pvr.c.
132            x)  Better GDROM support
133            x)  Modem
134            x)  PCI bridge/bus?
135            x)  Maple bus:
136                    x)  Correct controller input
137                    x)  Mouse input
138            x)  Software emulation of BIOS calls:
139                    x)  GD-ROM emulation: Use the GDROM device.
140                    x)  Use the VGA font as a fake ROM font. (Better than
141                        nothing.)
142            x)  Make as many as possible of the KOS examples run!
143            x)  More homebrew demos/games.
144            x)  SPU: Sound emulation (ARM cpu).
145            x)  VME processor emulation? "(Sanyo LC8670 "Potato")" according to
146                Wikipedia, LC86K87 according to Comstedt's page. See
147                http://www.maushammer.com/vmu.html for a good description of
148                the differences between LC86104C and the one used in the VME.
149    
150    Alpha:
151            x)  OSF1 PALcode, Virtual memory support.
152            x)  PALcode replacement! PAL1E etc opcodes...?
153            x)  Interrupt/exception/trap handling.
154            x)  Floating point exception correctness.
155            x)  More work on bootup memory and register contents.
156            x)  More Alpha machine types, so it could work with
157                OpenBSD, FreeBSD, and Linux too?
158    
159    SPARC (both the ISA and the machines):
160            o)  Implement Adress space identifiers; load/stores etc.
161            o)  Exception/trap/interrupt handling.
162            o)  Save/restore register windows etc! Both v9 and pre-v9!
163            o)  Finish the subcc and addcc flag computation code.
164            o)  Add more registers (floating point, control regs etc)
165            o)  Disassemly of some more instructions?
166            o)  Are sll etc 32-bit sign-extending or zero-extending?
167            o)  Floating point exception correctness.
168            o)  SPARC v8, v7 etc?
169            o)  More machine modes and devices.
170    
171    POWER/PowerPC:
172            x)  Fix DECR timer speed, so it matches the host.
173            x)  NetBSD/prep 3.x triggers a possible bug in the emulator:
174                <wdc_exec_command(0xd005e514,0xd60cdd30,0,8,..)>
175                  <ata_get_xfer(0,0xd60cdd30,0,8,..)>
176                    <0x26c550(&ata_xfer_pool,2,0,8,..)>
177                    <0x35c71c(0x3f27000,0,52,8,..)>
178                  <ata_exec_xfer(0xd005e4c8,0x3f27000,0,13,..)>
179                    <atastart(0xd005e4c8,0x3f27000,0,13,..)>
180                      <__wdccommand_start(0xd005e4c8,0x3f27000,0,13,..)>
181                        <bsw1(&prep_isa_io_space_tag,0x800001f6,0,176,..)>
182                    [ wdc: write to SDH: 0xb0 (sectorsize 2, lba=1, drive 1, head 0) ]
183                        <wdcwait(0xd005e4c8,72,64,0xbb8,..)>
184                          <0x198120(0xd005e4c8,72,64,0xbb8,..)>
185                            <bsr1(&prep_isa_io_space_tag,0,0,0xbb8,..)>
186                            <delay(100,0,0,0xbb8,..)>
187                Note: <bsr1(&prep_isa_io_space_tag,0,0,0xbb8,..)>
188            x)  PPC optimizations; instr combs
189            x)  64-bit stuff: either Linux on G5, or perhaps some hobbyist
190                    version of AIX? (if there exists such a thing)
191            x)  macppc: adb controller; keyboard (for framebuffer mode)
192            x)  make OpenBSD/macppc work (PCI controller stuff)
193            x)  Floating point exception correctness.
194            x)  Alignment exceptions.
195    
196    PReP:
197            x)  Clock time! ("Bad battery blah blah")
198    
199    Algor:
200            o)  Other models than the P5064?
201            o)  PCI interrupts... needed for stuff like the tlp NIC?
202    
203    BeBox:
204            o)  Interrupts. There seems to be a problem with WDC interrupts
205                "after a short while", although a few interrupts get through?
206            o)  Perhaps find a copy of BeOS and try it?
207    
208    Malta:
209            o)  The Linux/Malta kernel at people.debian.org/~ths/qemu/malta/
210                almost works:
211                    ./gxemul -x -o 'rd_start=0x80800000 rd_size=10000000 init=/bin/sh' -C 4KEc
212                      -e malta 0x80800000:people.debian.org/~ths/qemu/malta/initrd.gz
213                      people.debian.org/~ths/qemu/malta/vmlinux
214                (Remove "init=/bin/sh" to boot into the Debian installer.)
215                There are at least two things that need to be fixed:
216                    1. PCI IDE; make Linux oops.
217                    2. Implement the NIC.
218    
219    HPCmips:
220            x)  Mouse/pad support! :)
221            x)  A NIC? (As a PCMCIA device?)
222    
223    ARM:
224            o)  See netwinder_reset() in NetBSD; the current "an internal error
225                occured" message after reboot/halt is too ugly.
226            o)  Generic ARM "wait"-like instruction?
227            o)  try to get netbsd/evbarm 3.x or 4.x running (iq80321)
228            o)  make the xscale counter registers (ccnt) work
229            o)  make the ata controller usable for FreeBSD!
230            o)  Debian/cats crashes because of unimplemented coproc stuff.
231                fix this?
232    
233    Test machines:
234            o)  dev_fb block fill and copy
235            o)  dev_fb draw characters (from the built-in font)?
236            o)  dev_fb input device? mouse pointer coordinates and buttons
237                    (allow changes in these to cause interrupts as well?)
238            o)  Redefine the halt() function so that it stops "sometimes
239                soon", i.e. usage in demo code should be:
240                    for (;;) {
241                            halt();
242                    }
243    
244    Debugger:
245            o)  How does SMP debugging work? Does it simply use "threads"?
246                What if the guest OS (running on an emulated SMP machine)
247                has a usertask running, with userland threads?
248            o)  Try to make the debugger more modular and, if possible, reentrant!
249            o)  Memory dumps should be able to dump both physical and
250                virtual emulated memory.
251            o)  Evaluate expressions within []? That would allow stuff like
252                cpu[x] where x is an expression.
253            o)  "pc = pc + 4" doesn't work! Bug. Should work. ("pc=pc+4" works.)
254            o)  Settings:
255                    x)  Special handlers for Write!
256                            +)  MIPS coproc regs
257                            +)  Alpha/MIPS/SPARC zero registers
258                            +)  x86 64/32/16-bit registers
259                    x)  Value formatter for resulting output.
260            o)  Call stack display (back-trace) of emulated programs.
261            o)  Nicer looking output of register dumps, floating point registers,
262                etc. Warn about weird/invalid register contents.
263            o)  Ctrl-C doesn't enter the debugger on some OSes (HP-UX?)...
264    
265  Dyntrans:  Dyntrans:
266            x)  NOTE: ARM etc. that load pc-relative constants, on writes to
267          x)  Separate data and instruction translations?              pages that contain translations, the ENTIRE page must be
268                invalidated, not just the 1/32th that was code.
269          x)  Generalize the inline quick_pc_to_pointers?          x)  For 32-bit emulation modes, that have emulated TLBs: tlbindex
270                arrays of mapped pages? Things to think about:
271          x)  Call/return hints...                  x)  Only 32-bit mode! (64-bit => too much code)
272                    x)  One array for global pages, and one array _PER ASID_,
273          x)  More 64-bit stuff.                      for those archs that support that. On M88K, there should
274                        be one array for userspace, and one for supervisor, etc.
275                    x)  Larger-than-4K-pages must fill several bits in the array.
276                    x)  No TLB search will be necessary.
277                    x)  Total host space used, for 4 KB pages: 1 MB per table,
278                        i.e. 65 MB for 32-bit MIPS, 2 MB for M88K, if one byte
279                        is used as the tlb index.
280                    x)  (The index is actually +1, so that 0 means no hit.)
281            x)  "Merge" the cur_physpage and cur_ic_page variables/pointers to
282                one? I.e. change cur_ic_page to cur_physpage.ic_page or something.
283            x)  Instruction combination collisions? How to avoid easily...
284            x)  superh -- no hostpage for e.g. 0x8c000000. devices as ram!
285            x)  Think about how to do both SHmedia and SHcompact in a reasonable
286                way! (Or AMD64 long/protected/real, for that matter.)
287            x)  68K emulation; think about how to do variable instruction
288                lengths across page boundaries.
289            x)  Dyntrans with valgrind-inspired memory checker. (In memory_rw,
290                it would be reasonably simple to add; in each individual fast
291                load/store routine = a lot more work, and it would become
292                kludgy very fast.)
293            x)  Dyntrans with SMP... lots of work to be done here.
294            x)  Dyntrans with cache emulation... lots of work here as well.
295            x)  Remove the concept of base RAM completely; it would be more
296                generic to allow RAM devices to be used "anywhere".
297            o)  dev_mp doesn't work well with dyntrans yet
298            o)  In general, IPIs, CAS, LL/SC etc must be made to work with dyntrans
299            x)  Redesign/rethink the delay slot mechanism used for e.g. MIPS,
300                    so that it caches a translation (that is, an instruction
301                    word and the instr_call it was translated to the last
302                    time), so that it doesn't need to do slow
303                    to_be_translated for each end of page?
304            x)  Program Counter statistics:
305                    Per machine? What about SMP? All data to the same file?
306                    A debugger command should be possible to use to enable/
307                    disable statistics gathering.
308                    Configuration file option!
309            x)  Breakpoints:
310                    o) Physical vs virtual addresses!
311                    o) 32-bit vs 64-bit sign extension for MIPS, and others?
312            x)  INVALIDATION should cause translations in _all_ cpus to be
313                invalidated, e.g. on a write to a write-protected page
314                (containing code)
315            x)  16-bit encodings? (MIPS16, ARM Thumb, etc)
316          x)  Lots of other stuff: see src/cpus/README_DYNTRANS          x)  Lots of other stuff: see src/cpus/README_DYNTRANS
317            x)  Native code generation backends... think carefully about this.
318    
319    Simple Valgrind-like checks?
320            o)  Mark every address with bits which tell whether or not the address
321                has been written to.
322            o)  What should happen when programs are loaded?  Text/data, bss (zero
323                filled). But stack space and heap is uninitialized.
324            o)  Uninitialized local variables:
325                    A load from a place on the stack which has not previously
326                    been stored to => warning. Increasing the stack pointer using
327                    any available means should reset the memory to uninitialized.
328            o)  If calls to malloc() and free() can be intercepted:
329                    o)  Access to a memory area after free() => warning.
330                    o)  Memory returned by malloc() is marked as not-initialized.
331                    o)  Non-passive, but good to have: Change the argument
332                        given to malloc, to return a slightly larger memory
333                        area, i.e.  margin_before + size + margin_after,
334                        and return the pointer  + margin_before.
335                        Any access to the margin_before or _after space results
336                        in warnings. (free() must be modified to free the
337                        actually allocated address.)
338    
339    Better CD Image file support:
340            x)  Support CD formats that contain more than 1 track, e.g.
341                CDI files (?). These can then contain a mixture of e.g. sound
342                and data tracks, and booting from an ISO filesystem path
343                would boot from [by default] the first data track.
344                (This would make sense for e.g. Dreamcast CD images, or
345                possibly other live-CD formats.)
346    
347    Networking:
348            x)  Redesign of the networking subsystem, at least the NAT translation
349                    part. The current way of allowing raw ethernet frames to be
350                    transfered to/from the emulator via UDP should probably be
351                    extended to allow the frames to be transmitted other ways as
352                    well.
353            x)  Also adding support for connecting ttys (either to xterms, or to
354                    pipes/sockets etc, or even to PPP->NAT or SLIP->NAT :-).
355            x)  Documentation updates (!) are very important, making it easier to
356                    use the (already existing) network emulation features.
357            x)  Fix performance problems caused by only allowing a
358                single TCP packet to be unacked.
359            x)  Don't hardcode offsets into packets!
360            x)  Test with lower than 100 max tcp/udp connections,
361                to make sure that reuse works!
362            x)  Make OpenBSD work better as a guest OS!
363            x)  DHCP? Debian doesn't actually send DHCP packets, even
364                    though it claims to? So it is hard to test.
365            x)  Multiple networks per emulation, and let different
366                NICs in machines connect to different networks.
367            x)  Support VDE (vde.sf.net)? Easiest/cleanest (before a
368                redesign of the network framework has been done) is
369                probably to connect it using the current (udp) solution.
370            x)  Allow SLIP connections, possibly PPP, in addition to
371                ethernet?
372    
373    Cache simulation:
374            o)  Command line flags for:
375                    o)  CPU endianness?
376                    o)  Cache sizes? (multiple levels)
377            o)  Separate from the CPU concept, so that multi-core CPUs sharing
378                e.g. a L2 cache can be simulated (?)
379            o)  Instruction cache emulation is easiest (if separate from the
380                data cache); similar hack as the S;I; hack in cpu_dyntrans.c.
381                NOTE: if the architecture has a delay slot, then an instruction
382                slot can actually be executed as 2 instructions.
383            o)  Data cache emulation = harder; each arch's load/store routines
384                must include support? running one instruction at a time and
385                having a cpu-dependant lookup function for each instruction
386                is another option (easier to implement, but very very slow).
387    
388    Documentation:
389            x)  Update the documentation regarding the testmachine interrupts.
390            x)  Note about sandboxing/security:
391                    Not all emulated instructions fail in the way they would
392                    do on real hardware (e.g. a userspace program writing to
393                    a system register might work in GXemul, but it would
394                    fail on real hardware).  Sandbox = contain from the
395                    host OS. But the emulated programs will run "less
396                    securely".
397            x)  Try NetBSD/arc 4.x! (It seems to work with disk images!)
398            x)  NetBSD/pmax 4 install instructions: xterm instead of vt100!
399            x)  Rewrite the section about experimental devices, after the
400                framebuffer acceleration has been implemented, and demos
401                written. (Symbolic names instead of numbers; example
402                use cases, etc. Mention demo files that use the various
403                features?)
404            x)  "a very simple linear framebuffer device (for graphics output)"
405                under "which machines does gxemul emulate" ==> better
406                description?
407    
408    The Device subsystem:
409            x)  allow devices to be moved and/or changed in size (down to a
410                minimum size, etc, or up to a max size); if there is a collision,
411                return false. It is up to the caller to handle this situation!
412            x)  NOTE: Translations must be invalidated, both for
413                registering new devices, and for moving existing ones.
414                cpu->invalidate translation caches, for all CPUs that
415                are connected to a specific memory.
416    
417    PCI:
418            x)  Pretty much everything related to runtime configuration, device
419                slots, interrupts, etc must be redesigned/cleaned up. The current
420                code is very hardcoded and ugly.
421            o)  Allow cards to be added/removed during runtime more easily.
422            o)  Allow cards to be enabled/disabled (i/o ports, etc, like
423                NetBSD needs for disk controller detection).
424            o)  Allow devices to be moved in memory during runtime.
425            o)  Interrupts per PCI slot, etc. (A-D).
426            o)  PCI interrupt controller logic... very hard to get right,
427                because these differ a lot from one machine to the next.
428            x)  last write was ffffffff ==> fix this, it should be used
429                together with a mask to get the correct bits. also, not ALL
430                bits are size bits! (lowest 4 vs lowest 2?)
431            x)  add support for address fixups
432            x)  generalize the interrupt routing stuff (lines etc)
433    
434    Clocks and timers:
435            x)  Fix the PowerPC DECR interrupt speed! (MacPPC and PReP speed, etc.)
436            x)  DON'T HARDCODE 100 HZ IN cpu_mips_coproc.c!
437            x)  NetWinder timeofday is incorrect! Huh? grep -R for ta_rtc_read in
438                NetBSD sources; it doesn't seem to be initialized _AT ALL_?!
439            x)  Cobalt TOD is incorrect!
440            x)  Go through all other machines, one by one, and fix them.
441    
442    Config file parser:
443            o)  Rewrite it from scratch!
444            o)  Usage of any expression available through the debugger
445            o)  Allow interrupt controllers to be added! and interrupts
446                to be used in more ways than before
447            o)  Support for running debugger commands (like the -c
448                command line option)
449    
450    Floating point layer:
451            o)  make it common enough to be used by _all_ emulation modes
452            o)  implement correct error/exception handling and rounding modes
453            o)  implement more helper functions (i.e. add, sub, mul...)
454            o)  non-IEEE modes (i.e. x86)?
455    
456  Userland emulation:  Userland emulation:
457            x)  Try to prefix "/emul/mips/" or similar to all filenames,
458                and only if that fails, try the given filename.
459                Read this setting from an environment variable, and only
460                if there is none, fall back to hardcoded string.
461            x)  File descriptor (0,1,2) assumptions? Find and fix these?
462            x)  Dynamic linking!
463            x)  Lots of stuff; freebsd, netbsd, linux, ... syscalls.
464            x)  Initial register/stack contents (environment, command line args).
465            x)  Return value (from main).
466            x)  mmap emulation layer
467            x)  errno emulation layer
468            x)  ioctl emulation layer for all devices :-[
469            x)  struct conversions for many syscalls
470    
471    Sound:
472            x)  generic sound framework
473            x)  add one or more sound cards as devices; add a testmachine
474                sound card first?
475            x)  Dreamcast sound? Generic PCI sound cards?
476    
477    ASC SCSI controller:
478            x)  NetBSD/arc 2.0 uses the ASC controller in a way which GXemul
479                cannot yet handle. (NetBSD 1.6.2 works ok.) (Possibly a problem
480                in NetBSD itself, http://mail-index.netbsd.org/source-changes/
481                2005/11/06/0024.html suggests that.)
482                NetBSD 4.x seems to work? :)
483    
484    Caches / memory hierarchies: (this is mostly MIPS-specific)
485            o)  src/memory*.c: Implement correct cache emulation for
486                all CPU types. (currently only R2000/R3000 is implemented)
487                (per CPU, multiple levels should be possible, associativity etc!)
488            o)  R2000/R3000 isn't _100%_ correct, just almost correct :)
489            o)  Move the -S (fill mem with random) functionality into the
490                memory.c subsystem, not machine.c or wherever it is now
491            o)  ECC stuff, simulation of memory errors?  (Machine dependent)
492            o)  More than 4GB of emulated RAM, when run on a 32-bit host?
493                (using manual swap-out of blocks to disk, ugly)
494            o)  A global command line option should be used to turn
495                cache emulation on or off. When off, caches should be
496                faked like they are right now. When on, caches and
497                memory latencies should be emulated as correctly as
498                possible.
499    
500    File/disk/symbol handling:
501            o)  Make sure that disks can be added/removed during runtime!
502                (Perhaps this needs a reasonably large re-write.)
503            o)  Remove some of the complexity in file format guessing, for
504                    Ultrix kernels that are actually disk images?
505            o)  Remove temporary files (/tmp/gxemul.blahblah) if loading fails
506                for some reason (unrecognized file, etc).
507            o)  Better handling of tape files      
508            o)  Read function argument count and types from binaries? (ELF?)
509            o)  Better demangling of C++ names. Note: GNU's C++ differs from e.g.
510                Microsoft's C++, so multiple schemes must be possible. See
511                URL at top of src/symbol_demangle.c for more info.
512    
513    Userland ABI emulation:
514            o)  see src/useremul.c
515    
516    Better framebuffer and X-windows functionality:
517            o)  Do a complete rewrite of the framebuffer/console stuff, so that:
518                    1)  It does not rely on X11 specifically.
519                    2)  It is possible to interact with emulated framebuffers
520                        and consoles "remotely", e.g. via a web page which
521                        controls multiple virtualized machines.
522                    3)  It is possible to run on (hypothetical) non-X11
523                        graphics systems.
524            o)  Generalize the update_x1y1x2y2 stuff to an extend-region()
525                function...
526            o)  -Yx sometimes causes crashes.
527            o)  Simple device access to framebuffer_blockcopyfill() etc,
528                and text output (using the built-in fonts), for dev_fb.
529            o)  CLEAN UP the ugly event code
530            o)  Mouse clicks can be "missed" in the current system; this is
531                not good. They should be put on a stack of some kind.
532            o)  More 2D and 3D framebuffer acceleration.
533            o)  Non-resizable windows?  Or choose scaledown depending
534                    on size (and center the image, with a black border).
535            o)  Different scaledown on different windows?
536            o)  Non-integral scale-up? (E.g. 640x480 -> 1024x768)
537            o)  Switch scaledown during runtime? (Ala CTRL-ALT-plus/minus)
538            o)  Bug reported by Elijah Rutschman on MacOS with weird
539                keys (F5 = cursor down?).
540            o)  Keyboard and mouse events:
541                    x)  Do this for more machines than just DECstation
542                    x)  more X11 cursor keycodes
543                    x)  Keys like CTRL, ALT, SHIFT do not get through
544                        by themselves (these are necessary for example
545                        to change the font of an xterm in X in the
546                        emulator)
547            o)  Generalize the framebuffer stuff by moving _ALL_ X11
548                    specific code to a separate module.
549    
550          x)  Lots of stuff.  -------------------------------------------------------------------------------
   
         x)  Dynamic linking? Hm.  
   
 ===============================================================================  
   
 Lower priority, but still important:  
   
         Redesign the entire "mainbus" concept:  
                 o)  Easily configurable interrupt routing in SMP systems.  
                 o)  Specific clock/bus speeds, cpu speeds etc.  
                 o)  Synchronization over network?  
   
         Caches / memory hierarchies: (this is mostly MIPS-specific)  
                 o)  MIPS coproc.c: bits in config registers should reflect  
                     correct cache sizes for _all_ CPU types. (currently only  
                     implemented for R4000, R1x000, and a few others)  
                 o)  src/memory*.c: Implement correct cache emulation for  
                     all CPU types. (currently only R2000/R3000 is implemented)  
                     (per CPU, multiple levels should be possible,  
                     associativity etc!)  
                 o)  R2000/R3000 isn't _100%_ correct, just almost correct :)  
                 o)  Move the -S (fill mem with random) functionality into the  
                     memory.c subsystem, not machine.c or wherever it is now  
                 o)  ECC stuff, simulation of memory errors?  (Machine dependant)  
                 o)  More than 4GB of emulated RAM, when run on a 32-bit host?  
                     (using manual swap-out of blocks to disk, ugly)  
                 o)  A global command line option should be used to turn  
                     cache emulation on or off. When off, caches should be  
                     faked like they are right now. When on, caches and  
                     memory latencies should be emulated as correctly as  
                     possible.  
   
         Network layer:  
                 o)  Multiple networks per emulation, and let different  
                     NICs in machines connect to different networks.  
                 o)  many other issues: see src/net.c  
   
         MIPS CPU emulation:  
                 o)  i386 bintrans backend: movn etc, slt[u] for  
                         64-bit mode, 64-bit shifts etc  
                 o)  Instructions:  
                         o)  All ISAs:  
                                 o)  Floating point exception handling, and  
                                         add more instructions.  
                                 o)  Finish the MIPS16 translator, and test it!  
                                 o)  MIPS ISA I, II, III, IV  
                                 o)  MIPS V (SIMD vector stuff?)  
                                 o)  MDMX  (MIPS Digital Media Extension)  
                                 o)  MIPS 3D  
                                 o)  MIPS MT (Multi-thread stuff) (What's this?)  
                         o)  Warn about mis-used bit fields (ie bits that  
                             should be all zeroes, warn about if they are not)!  
                             Both for coprocessor registers and for instruction  
                             opcodes.  
                         o)  the special2 stuff is a mess right now  
                         o)  warn and/or cause exceptions for unimplemented  
                             instructions (depending on CPU type)  
                 o)  R2000/R3000:  
                         x)  R3000 "tri-byte stores". (What's this?)  
                 o)  R4000 and others:  
                         x)  watchhi/watchlo exceptions, and other exception  
                             handling details  
                 o)  R10000 and others:  (R12000, R14000 ?)  
                         x)  memory space, exceptions, ...  
                         x)  use cop0 framemask for tlb lookups  
                             (http://techpubs.sgi.com/library/tpl/cgi-bin/getdoc.cgi/hdwr/bks/SGI_Developer/books/R10K_UM/sgi_html/t5.Ver.2.0.book_284.html)  
                 o)  Implement load delays?  Warnings on interlocks.  
                 o)  Implement all coprocessor 0 bits / functions.  
                         x)  coproc 0 selectors! (R4000 ?)  
                 o)  R4300 (nintendo64, no mmu?), R5900 (playstation2, weird  
                         TLB/cache? 128-bit GPRs, new instructions),  
                         4K (note: NOT R4000), 5K (note: NOT R5000),  
                         R6000 (ISA II), R8000  
                 o)  Multi-cpu stuff:  
                         +)  Interrupt routing (ie devices vs mainbus, or  
                             connect each device to a fixed cpu)  
                         +)  SGI's NUMA architecture. Study  
                                 x)  Linux sources  
                                 x)  SGI's specs on NUMA address space  
                         +)  Ultrix?  NetBSD doesn't do SMP on MIPS yet :-(  
                         +)  Own experiments with ycx2.  
   
         File/disk handling:  
                 o)  Better handling of tape files  
   
         Debugger:  
                 o)  Read function argument count and types from binaries? (ELF?)  
                 o)  Demangle C++ names.  
                 o)  see src/debugger.c for more stuff  
   
         Userland ABI emulation:  
                 o)  see src/useremul.c  
   
         Terminal/console stuff:  
                 o)  allow emulated serial ports to be connected to the outside  
                     world in a more generic way, or even to other emulated  
                     machines(!)  
   
         Regression tests.  (Needs to be totally rewritten, the old framework  
                 was removed because it was useless.)  
   
         Save state of the whole emulated machine, to be able to load it back  
                 in later?  (Memory, all device's states, all registers and  
                 so on.  Like taking a snapshot. (SimOS seems to do this,  
                 according to its website.))  
   
         Better X-windows functionality:  
                 o)  CLEAN UP the ugly event code  
                 o)  Mouse clicks can be "missed" in the current system; this is  
                     not good. They should be put on a stack of some kind.  
                 o)  More 2D and 3D framebuffer acceleration.  
                 o)  Non-resizable windows?  Or choose scaledown depending  
                         on size (and center the image, with a black border).  
                 o)  Different scaledown on different windows?  
                 o)  Switch scaledown during runtime? (Ala CTRL-ALT-plus/minus)  
                 o)  Keyboard and mouse events:  
                         x)  Do this for more machines than just DECstation  
                         x)  more X11 cursor keycodes  
                         x)  Keys like CTRL, ALT, SHIFT do not get through  
                             by themselves (these are necessary for example  
                             to change the font of an xterm in X in the  
                             emulator)  
                 o)  Generalize the framebuffer stuff by moving _ALL_ X11  
                         specific code to src/x11.c!  
   
         Statistics:  (this could be interesting)  
                 o)  Save to file and show graphics. It should be possible to  
                     run gxemul after a simulation to just show the graphics,  
                     or convert to a .ppm or .tga or similar.  
                 o)  memory accesses (to measure cache efficiency and  
                         page coloring efficiency)  
                 o)  nr of simultaneous ASIDs in use in the TLB, for MIPS  
                 o)  percentage of time spent in different "states", such as  
                     running userland code, kernel code, or idling (for CPUs  
                     that have such an instruction, or whenever the PC is  
                     inside a specific idle-function (address range)).  
                     Possible additional state (for example on R3000): caches  
                     disabled.  
                 o)  position of read/write on (SCSI) disks  
551    

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